2000
Authors
Azevedo, AL; Sousa, JP;
Publication
JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY
Abstract
From the general trend towards global markers and a growing customer orientation, new concepts and forms of organisation are emerging, such as distributed or networked enterprises. One key requirement of these new paradigms is the availability of models and tools to support order negotiation with the optimisation of manufacturing routes and logistics and ensuring the co-ordination of all participating entities. We address the problem of planning an incoming customer order to be produced in a distributed (multi-site) and multi-stage production system, in particular, we have used as a case study the industry of semiconductors (in the business area of application specific integrated circuits). The problem is tackled in a hierarchical model, in two levels: there is a global network planning procedure, and a set of local capacity models associated to the different production units reflecting their particular features. An approach based on simulated annealing is presented, as well as a specially designed constructive heuristic, that takes into account many of the real world constraints and complexities. The general performance of the simulated annealing algorithm is assessed through some preliminary computational experiments. Finally, some concluding remarks and current directions of research are presented.
2000
Authors
Azevedo, AL; Sousa, JP;
Publication
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
Abstract
Traditional Production Planning and Control systems do not successfully deal with new organisational forms of manufacturing, like production "islands", product oriented or customer driven production. These current trends lead in practice to a strong decentralisation of production management tasks and to an "object oriented structuring" of the manufacturing process. Planning and operation in this global environment requires new skills and new approaches, namely, the co-ordination of global networks of manufacturing units and of large complex supply chains. In this paper, we present a decentralised information system designed to address the tasks of production planning that result from sales orders, originated in customers located anywhere in the world, and accomplished through a distributed manufacturing network. The system addresses the requirements of a make-to-order environment and is hopefully able to produce realistic satisfactory delivery dates. The information infrastructure designed and implemented using distributed object-oriented technology with a component based architecture has proven to be efficient and powerful, satisfying all the major tight requirements of information systems in an environment of distributed manufacturing.
2000
Authors
Viana, A; de Sousa, JP;
Publication
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH
Abstract
Although single objective metaheuristics are widely spread and applied in many combinatorial optimisation problems, only very recently have multiobjective metaheuristics (MOMH) been designed and used in practice. They aim at obtaining good approximations of the set of nondominated solutions of a problem, in an efficient way. In this work, we have applied multiobjective versions of simulated annealing and taboo search to the resource constrained project scheduling problem (RCPSP), in order to minimise the makespan, the "weighted" lateness of activities and the violation of resource constraints. Computational experience performed on randomly generated instances shows that this general approach is flexible, effective and able to deal with multiple objectives and with variations in the problem structure.
2000
Authors
Azevedo, AL; Sousa, JP; Oliveira, RT;
Publication
MULTI-AGENT-SYSTEMS IN PRODUCTION
Abstract
Current Production Planning and Control Systems do not in general satisfy the needs and challenges of production networks, as they lack the capacity to appropriately support a co-ordinated and effective communication between heterogeneous manufacturing sites. This paper presents a new approach, based on the multi-agent systems paradigm, for a planning (order negotiation) system suitable for distributed and virtual enterprises. The infrastructure and planning methodology (based on negotiations) proposed in this paper, have been designed for planning orders, involving a large number of scattered manufacturing plants, used in different production stages, connected through a complex logistic subsystem. A Decision Support System has been designed around an architecture based on several intelligent agents communicating through the Knowledge Query Manipulation Language (KQML). Copyright (C) 1999 IFAC.
2000
Authors
Soares, A; Schmidt, C; Gaida, W;
Publication
AUTOMATED SYSTEMS BASED ON HUMAN SKILL 2000: JOINT DESIGN OF TECHNOLOGY AND ORGANISATION
Abstract
This paper gives an overview of a trans-european research and development project where a manufacturing team information system was developed. The focus is on the process of requirements analysis and specification, and on the prototype evaluation. Special emphasis is given to the effectiveness of the users involvement in the process. Copyright (C) 2000 IFAC.
1999
Authors
Alves, JC; Ferreira, JC; Albuquerque, C; Oliveira, JF; Ferreira, JS; Matos, JS;
Publication
7th IEEE Symposium on Field-Programmable Custom Computing Machines (FCCM '99), 21-23 April 1999, Napa, CA, USA
Abstract
The nesting problem consists of defining the cutting plan of a piece of raw material in smaller irregular shapes, and has applications in the apparel and footwear industries. Due to its NP-hard nature, the optimal solution can only be guaranteed by exhaustively trying all possible solutions and choosing the best one. Because this is impractical in real-life industrial problems, automatic approaches are based on optimization meta-heuristics that search for sub-optimal but good enough solutions. These optimization techniques rely on the construction and evaluation of several solutions, thus requiring heavy geometric manipulation of the irregular polygons that constitute the problem data. Efficient processing of this geometric information is thus necessary to make effective fully automatic approaches to nesting problems in industrial environments. This paper describes Fafner, an FPGA-based custom computing machine that is used to accelerate the geometric operations, that are in the core of heuristic solutions to the nesting problem. The system is used as an auxiliary processor attached to a low cost personal computer, and combines a custom programmable processor with an array of custom circuits for the processing of irregular polygons.
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.